1
|
Haktaniyan M, Sharma R, Bradley M. Size-Controlled Ammonium-Based Homopolymers as Broad-Spectrum Antibacterials. Antibiotics (Basel) 2023; 12:1320. [PMID: 37627740 PMCID: PMC10452032 DOI: 10.3390/antibiotics12081320] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/31/2023] [Revised: 08/08/2023] [Accepted: 08/14/2023] [Indexed: 08/27/2023] Open
Abstract
Ammonium group containing polymers possess inherent antimicrobial properties, effectively eliminating or preventing infections caused by harmful microorganisms. Here, homopolymers based on monomers containing ammonium groups were synthesized via Reversible Addition Fragmentation Chain Transfer Polymerization (RAFT) and evaluated as potential antibacterial agents. The antimicrobial activity was evaluated against Gram-positive (M. luteus and B. subtilis) and Gram-negative bacteria (E. coli and S. typhimurium). Three polymers, poly(diallyl dimethyl ammonium chloride), poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride), and poly(vinyl benzyl trimethylammonium chloride), were examined to explore the effect of molecular weight (10 kDa, 20 kDa, and 40 kDa) on their antimicrobial activity and toxicity to mammalian cells. The mechanisms of action of the polymers were investigated with dye-based assays, while Scanning Electron Microscopy (SEM) showed collapsed and fused bacterial morphologies due to the interactions between the polymers and components of the bacterial cell envelope, with some polymers proving to be bactericidal and others bacteriostatic, while being non-hemolytic. Among all the homopolymers, the most active, non-Gram-specific polymer was poly([2-(methacryloyloxy)ethyl]trimethylammonium chloride), with a molecular weight of 40 kDa, with minimum inhibitory concentrations between 16 and 64 µg/mL, showing a bactericidal mode of action mediated by disruption of the cytoplasmic membrane. This homopolymer could be useful in biomedical applications such as surface dressings and in areas such as eye infections.
Collapse
Affiliation(s)
- Meltem Haktaniyan
- EaStCHEM, School of Chemistry, University of Edinburgh, Joseph Black Building, West Mains Road, Edinburgh EH9 3FJ, UK; (M.H.); (R.S.)
| | - Richa Sharma
- EaStCHEM, School of Chemistry, University of Edinburgh, Joseph Black Building, West Mains Road, Edinburgh EH9 3FJ, UK; (M.H.); (R.S.)
| | - Mark Bradley
- EaStCHEM, School of Chemistry, University of Edinburgh, Joseph Black Building, West Mains Road, Edinburgh EH9 3FJ, UK; (M.H.); (R.S.)
- Precision Healthcare University Research Institute, Queen Mary University of London, Whitechapel, Empire House, London E1 1HH, UK
| |
Collapse
|
2
|
Šálek P, Trousil J, Nováčková J, Hromádková J, Mahun A, Kobera L. Poly[2-(dimethylamino)ethyl methacrylate- co-ethylene dimethacrylate]nanogel by dispersion polymerization for inhibition of pathogenic bacteria. RSC Adv 2021; 11:33461-33470. [PMID: 35497568 PMCID: PMC9042309 DOI: 10.1039/d1ra06231j] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2021] [Accepted: 10/07/2021] [Indexed: 02/03/2023] Open
Abstract
Bacterial infections and antimicrobial resistance are one of the major public health problems and various strategies to prevent potential threats have been developed. Protonated polymers were proven as efficient agents against several microbial pathogens. Poly[2-(dimethylamino)ethyl methacrylate] (PDMAEMA) linear polymer and its copolymers represent one example of functional materials which inhibit the growth of both harmful Gram-negative and Gram-positive bacteria. However, the antimicrobial effect of positively charged PDMAEMA particles has been never tested. In this report, we deeply studied several parameters of free-radical polymerization, including the effect of crosslinking monomer, medium composition, solvency and polarity, and type and concentration of initiator and stabilizer, to fabricate high-quality poly[2-(dimethylamino)ethyl methacrylate-co-ethylene dimethacrylate] (PDMAEMA-EDMA) nanogel. We successfully found that dispersion polymerization in water/2-methoxyethanol medium (80/20 w/w), initiated with 0.2 wt% potassium persulfate (KPS) and stabilized with 0.5 wt% poly(vinyl alcohol) (PVA), produced a well-defined and sub-micron 167 nm PDMAEMA-EDMA nanogel. Bactericidal activity of the quaternized PDMAEMA-EDMA nanogel was assessed via time-kill curve assay against two Gram-positive and Gram-negative pathogenic bacteria, namely Staphylococcus aureus (S. aureus) and Acinetobacter baumannii (A. baumannii). The results illustrated that the quaternized PDMAEMA-EDMA nanogel acted as an effective bactericidal agent against both tested bacteria.
Collapse
Affiliation(s)
- Petr Šálek
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic Heyrovského nám. 2 162 06 Prague 6 Czech Republic
| | - Jiří Trousil
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic Heyrovského nám. 2 162 06 Prague 6 Czech Republic
| | - Jitka Nováčková
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic Heyrovského nám. 2 162 06 Prague 6 Czech Republic
| | - Jiřina Hromádková
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic Heyrovského nám. 2 162 06 Prague 6 Czech Republic
| | - Andrii Mahun
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic Heyrovského nám. 2 162 06 Prague 6 Czech Republic .,Department of Physical and Macromolecular Chemistry, Faculty of Science, Charles University Hlavova 8 128 40 Prague 2 Czech Republic
| | - Libor Kobera
- Institute of Macromolecular Chemistry, Academy of Sciences of the Czech Republic Heyrovského nám. 2 162 06 Prague 6 Czech Republic
| |
Collapse
|
3
|
Yandi W, Mieszkin S, Callow ME, Callow JA, Finlay JA, Liedberg B, Ederth T. Antialgal activity of poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes against the marine alga Ulva. BIOFOULING 2017; 33:169-183. [PMID: 28151007 DOI: 10.1080/08927014.2017.1281409] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/21/2016] [Accepted: 01/09/2017] [Indexed: 06/06/2023]
Abstract
Marine biofouling has detrimental effects on the environment and economy, and current antifouling coatings research is aimed at environmentally benign, non-toxic materials. The possibility of using contact-active coatings is explored, by considering the antialgal activity of cationic poly(2-(dimethylamino)ethyl methacrylate) (PDMAEMA) brushes. The antialgal activity was investigated via zoospore settlement and sporeling growth assays of the marine algae Ulva linza and U. lactuca. The assay results for PDMAEMA brushes were compared to those for anionic and neutral surfaces. It was found that only PDMAEMA could disrupt zoospores that come into contact with it, and that it also inhibits the subsequent growth of normally settled spores. Based on the spore membrane properties, and characterization of the PDMAEMA brushes over a wide pH range, it is hypothesized that the algicidal mechanisms are similar to the bactericidal mechanisms of cationic polymers, and that further development could lead to successful contact-active antialgal coatings.
Collapse
Affiliation(s)
- Wetra Yandi
- a Division of Molecular Physics , IFM, Linköping University , Linköping , Sweden
| | - Sophie Mieszkin
- b School of Biosciences , University of Birmingham , Birmingham , UK
| | - Maureen E Callow
- b School of Biosciences , University of Birmingham , Birmingham , UK
| | - James A Callow
- b School of Biosciences , University of Birmingham , Birmingham , UK
| | - John A Finlay
- b School of Biosciences , University of Birmingham , Birmingham , UK
| | - Bo Liedberg
- a Division of Molecular Physics , IFM, Linköping University , Linköping , Sweden
- c Centre for Biomimetic Sensor Science, School of Materials Science and Engineering , Nanyang Technological University , Singapore , Singapore
| | - Thomas Ederth
- a Division of Molecular Physics , IFM, Linköping University , Linköping , Sweden
| |
Collapse
|
4
|
Copper promotes TFF1-mediated Helicobacter pylori colonization. PLoS One 2013; 8:e79455. [PMID: 24236136 PMCID: PMC3827375 DOI: 10.1371/journal.pone.0079455] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/03/2013] [Accepted: 10/01/2013] [Indexed: 02/08/2023] Open
Abstract
The trefoil peptides (TFF1, TFF2 and TFF3) are a family of small highly conserved proteins that play an essential role in epithelial regeneration within the gastrointestinal tract, where they are mainly expressed. TFF1 expression is strongly induced after mucosal injury and it has been proposed that tff1 functions as a gastric tumor suppressor gene. Several studies confirm that tff1 expression is frequently lost in gastric cancer because of deletions, mutations or methylation of the tff1 promoter. Infection by Helicobacter pylori (H. pylori) results in chronic gastritis and it can lead to the development of gastric or duodenal ulcers. Moreover, it is known that there is a strong link to the development of gastric cancer. It has been shown that H. pylori interacts with the dimeric form of TFF1 and that the rough form of lipopolysaccharide mediates this interaction. We have previously reported that the carboxy-terminus of TFF1 is able to specifically bind copper ions (Cu) and that Cu binding favours the homodimerization of the peptide, thus enhancing its motogenic activity. Here, we report that the Cu-TFF1 cuprocomplex promotes adherence of H. pylori to epithelial cells. Adherence of H. pylori to gastric adenocarcinoma cells, AGS AC1 cells, induced to hyper-express TFF1 was enhanced compared to noninduced cells. Copper further promoted this interaction. A H. pylori mutant unable to bind TFF1 did not show enhanced infection of induced cells. Cu treatment induced a thickening of the mucus layer produced by the colorectal adenocarcinoma mucus secreting, goblet cells, HT29-E12 and promoted H. pylori colonisation. Finally, SPR analysis shows that the C-terminus of TFF1, involved in the binding of copper, is also able to selectively bind H. pylori RF-LPS.
Collapse
|
5
|
Divergent mechanisms of interaction of Helicobacter pylori and Campylobacter jejuni with mucus and mucins. Infect Immun 2013; 81:2838-50. [PMID: 23716616 DOI: 10.1128/iai.00415-13] [Citation(s) in RCA: 45] [Impact Index Per Article: 4.1] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/20/2022] Open
Abstract
Helicobacter pylori and Campylobacter jejuni colonize the stomach and intestinal mucus, respectively. Using a combination of mucus-secreting cells, purified mucins, and a novel mucin microarray platform, we examined the interactions of these two organisms with mucus and mucins. H. pylori and C. jejuni bound to distinctly different mucins. C. jejuni displayed a striking tropism for chicken gastrointestinal mucins compared to mucins from other animals and preferentially bound mucins from specific avian intestinal sites (in order of descending preference: the large intestine, proximal small intestine, and cecum). H. pylori bound to a number of animal mucins, including porcine stomach mucin, but with less avidity than that of C. jejuni for chicken mucin. The strengths of interaction of various wild-type strains of H. pylori with different animal mucins were comparable, even though they did not all express the same adhesins. The production of mucus by HT29-MTX-E12 cells promoted higher levels of infection by C. jejuni and H. pylori than those for the non-mucus-producing parental cell lines. Both C. jejuni and H. pylori bound to HT29-MTX-E12 mucus, and while both organisms bound to glycosylated epitopes in the glycolipid fraction of the mucus, only C. jejuni bound to purified mucin. This study highlights the role of mucus in promoting bacterial infection and emphasizes the potential for even closely related bacteria to interact with mucus in different ways to establish successful infections.
Collapse
|
6
|
Hall T, Dymock D, Corfield AP, Weaver G, Woodward M, Berry M. Bacterial invasion of HT29-MTX-E12 monolayers: effects of human breast milk. J Pediatr Surg 2013; 48:353-7; discussion 357-8. [PMID: 23414864 DOI: 10.1016/j.jpedsurg.2012.11.021] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/07/2012] [Accepted: 11/12/2012] [Indexed: 11/17/2022]
Abstract
AIM The supramucosal gel, crucial for gut barrier function, might be compromised in necrotizing enterocolitis (NEC). Breast milk is associated with a reduced incidence of NEC. We compared the effects of human breast milk (BM) versus a neonatal formula, Nutriprem 1 (FF), on adherence, internalisation, and penetration of NEC-associated Escherichia coli through monolayers of mucus producing intestinal cells, HT29-MTX-E12 (E12). METHODS E12 cells were grown to confluence on membranes permeable to bacteria. E. coli, reference strain and isolated from a NEC-affected intestine, were cultured in LB broth, labelled with fluorescein and biotinylated. Bacteria were suspended in tissue culture medium (TC) or mixtures of TC with BM or FF and applied to the E12 cultures. Bacterial numbers were assessed by fluorescence. DyLight 650-labelled neutravidin, which cannot cross cell membrane, evaluated extracellular bacteria. Fluorescence of basolateral medium was measured to quantify translocation. Bacterial concentrations were compared using the Mann Whitney U test. RESULTS After 1h exposure, E12 cultures adhered or internalised more NEC-derived bacteria than standard strain E. coli and more suspended in FF than BM (P<0.001). A greater proportion of NEC-derived bacteria internalised when suspended in TC or BM. In FF, the NEC-derived strain internalised least. More translocation occurred in BM incubations compared to FF in the first 1-4h: NEC-E. coli less than the reference strain. After 24h translocated bacterial populations were equal. CONCLUSION In this pilot study, breast milk was associated with relatively less adhesion and internalisation of NEC-associated E. coli to mucus covered E12s compared to formula milk.
Collapse
Affiliation(s)
- Tim Hall
- University of Bristol, School of Clinical Sciences, Bristol Dental Hospital, Bristol, BS1 2LY, UK
| | | | | | | | | | | |
Collapse
|
7
|
Dolan B, Naughton J, Tegtmeyer N, May FEB, Clyne M. The interaction of Helicobacter pylori with the adherent mucus gel layer secreted by polarized HT29-MTX-E12 cells. PLoS One 2012; 7:e47300. [PMID: 23056622 PMCID: PMC3466223 DOI: 10.1371/journal.pone.0047300] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/29/2012] [Accepted: 09/13/2012] [Indexed: 12/13/2022] Open
Abstract
Helicobacter pylori colonises the gastric mucosa of humans. The majority of organisms live in mucus. These organisms are an important reservoir for infection of the underlying epithelium. Cell culture models for H. pylori infection do not normally possess a mucus layer. The interaction of H. pylori with TFF1, a member of the trefoil factor family found in gastric mucin, is mediated by lipopolysaccharide. To test the hypothesis that the interaction of H. pylori with TFF1 promotes mucus colonization we characterised the interaction of H. pylori with a mucus secreting cell line, HT29-MTX-E12. An isogenic mutant of H. pylori with truncated core oligosaccharides was produced and binding to TFF1 and ability to colonise HT29-MTX-E12 cells determined. The adherent mucus layer of HT29-MTX-E12 cells contained the gastric mucin MUC5AC and trefoil factors, TFF1 and TFF3. H. pylori was found within the mucus layer in discrete clusters and in close association with TFF1. It also interacted with the membrane bound mucin MUC1 and replicated when co-cultured with the cells. An isogenic mutant of H. pylori with a truncated LPS core did not interact with TFF1, and colonization of HT29-MTX-E12 cells was reduced compared to the wild-type strain (p<0.05). Preincubation of cells with wild type LPS but not with truncated LPS resulted in reduced colonization by H. pylori. These results demonstrate that the interaction of TFF1 with H. pylori is important for colonization of gastric mucus and the core oligosaccharide of H. pylori LPS is critical for this interaction to occur. HT29-MTX-E12 cells are a useful system with which to study the interaction of bacteria with mucosal surfaces and the effect of such interactions on mediating colonization.
Collapse
Affiliation(s)
- Brendan Dolan
- University College Dublin, School of Medicine and Medical Science, Dublin, Ireland
- Conway Institute of Biomolecular and Biomedical Science, Belfield, Dublin, Ireland
- The National Childrens Research Centre, Dublin, Ireland
| | - Julie Naughton
- University College Dublin, School of Medicine and Medical Science, Dublin, Ireland
- School of Biomolecular and Biomedical Science, Dublin, Ireland
| | - Nicole Tegtmeyer
- School of Biomolecular and Biomedical Science, Dublin, Ireland
- Conway Institute of Biomolecular and Biomedical Science, Belfield, Dublin, Ireland
| | - Felicity E. B. May
- Faculty of Medical Sciences, University of Newcastle upon Tyne, Newcastle upon Tyne, United Kingdom
| | - Marguerite Clyne
- University College Dublin, School of Medicine and Medical Science, Dublin, Ireland
- Conway Institute of Biomolecular and Biomedical Science, Belfield, Dublin, Ireland
- The National Childrens Research Centre, Dublin, Ireland
- * E-mail:
| |
Collapse
|
8
|
Keely S, Kelly CJ, Weissmueller T, Burgess A, Wagner BD, Robertson CE, Harris JK, Colgan SP. Activated fluid transport regulates bacterial-epithelial interactions and significantly shifts the murine colonic microbiome. Gut Microbes 2012; 3:250-60. [PMID: 22614705 PMCID: PMC3427217 DOI: 10.4161/gmic.20529] [Citation(s) in RCA: 48] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Within the intestinal mucosa, epithelial cells serve multiple functions to partition the lumen from the lamina propria. As part of their natural function, intestinal epithelial cells actively transport electrolytes with passive water movement as a mechanism for mucosal hydration. Here, we hypothesized that electrogenic Cl(-) secretion, and associated mucosal hydration, influences bacterial-epithelial interactions and significantly influences the composition of the intestinal microbiota. An initial screen of different epithelial secretagogues identified lubiprostone as the most potent agonist for which to define these principles. In in vitro studies using cultured T84 cells, lubiprostone decreased E. coli translocation in a concentration-dependent manner (p < 0.001) and decreased S. typhimurium internalization and translocation by as much as 71 ± 6% (p < 0.01). Such decreases in bacterial translocation were abolished by inhibition of electrogenic Cl(-) secretion and water transport using the Na/K/Cl(-) antagonist bumetanide (p < 0.01). Extensions of these findings to microbiome analysis in vivo revealed that lubiprostone delivered orally to mice fundamentally shifted the intestinal microbiota, with notable changes within the Firmicutes and Bacteroidetes phyla of resident colonic bacteria. Such findings document a previously unappreciated role for epithelial Cl(-) secretion and water transport in influencing bacterial-epithelial interactions and suggest that active mucosal hydration functions as a primitive innate epithelial defense mechanism.
Collapse
Affiliation(s)
- Simon Keely
- Mucosal Inflammation Program; Department of Medicine; University of Colorado School of Medicine; Aurora, CO USA,School of Biomedical Sciences and Pharmacy; University of Newcastle; New Castle, Australia
| | - Caleb J. Kelly
- Mucosal Inflammation Program; Department of Medicine; University of Colorado School of Medicine; Aurora, CO USA
| | - Thomas Weissmueller
- Mucosal Inflammation Program; Department of Medicine; University of Colorado School of Medicine; Aurora, CO USA,Department of Anesthesiology and Perioperative Pain; Brigham and Women’s Hospital and Harvard Medical School; Boston, MA USA
| | - Adrianne Burgess
- Mucosal Inflammation Program; Department of Medicine; University of Colorado School of Medicine; Aurora, CO USA
| | - Brandie D. Wagner
- Department of Biostatistics and Informatics; Colorado School of Public Health; University of Colorado Denver; Aurora, CO USA
| | - Charles E. Robertson
- Department of Molecular; Cellular and Developmental Biology; University of Colorado; Boulder, CO USA
| | - J. Kirk Harris
- Department of Pediatrics, Pulmonary Medicine; Children’s Hospital Colorado; Aurora, CO USA
| | - Sean P. Colgan
- Mucosal Inflammation Program; Department of Medicine; University of Colorado School of Medicine; Aurora, CO USA,Correspondence to: Sean P. Colgan,
| |
Collapse
|
9
|
|
10
|
Abstract
Chronic obstructive pulmonary disease (COPD) and inflammatory bowel diseases (IBDs) are chronic inflammatory diseases of mucosal tissues that affect the respiratory and gastrointestinal tracts, respectively. They share many similarities in epidemiological and clinical characteristics, as well as in inflammatory pathologies. Importantly, both conditions are accompanied by systemic comorbidities that are largely overlooked in both basic and clinical research. Therefore, consideration of these complications may maximize the efficacy of prevention and treatment approaches. Here, we examine both the intestinal involvement in COPD and the pulmonary manifestations of IBD. We also review the evidence for inflammatory organ cross-talk that may drive these associations, and discuss the current frontiers of research into these issues.
Collapse
|
11
|
Keely S, Feighery L, Campion DP, O’Brien L, Brayden DJ, Baird AW. Chloride-led Disruption of the Intestinal Mucous Layer Impedes Salmonella Invasion: Evidence for an ‘Enteric Tear’ Mechanism. Cell Physiol Biochem 2011; 28:743-52. [DOI: 10.1159/000335768] [Citation(s) in RCA: 17] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/24/2011] [Indexed: 01/20/2023] Open
|
12
|
Rawlinson LAB, Ryan SM, Mantovani G, Syrett JA, Haddleton DM, Brayden DJ. Antibacterial effects of poly(2-(dimethylamino ethyl)methacrylate) against selected gram-positive and gram-negative bacteria. Biomacromolecules 2010; 11:443-53. [PMID: 20025269 DOI: 10.1021/bm901166y] [Citation(s) in RCA: 164] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
Antimicrobial coatings can reduce the occurrence of medical device-related bacterial infections. Poly(2-(dimethylamino ethyl)methacrylate) (pDMAEMA) is one such polymer that is being researched in this regard. The aims of this study were to (1) elucidate pDMAEMA's antimicrobial activity against a range of Gram-positive and Gram-negative bacteria and (2) to investigate its antimicrobial mode of action. The methods used include determination of minimum inhibitory concentration (MIC) values against various bacteria and the effect of pH and temperature on antimicrobial activity. The ability of pDMAEMA to permeabilise bacterial membranes was determined using the dyes 1-N-phenyl-naphthylamine and calcein-AM. Flow cytometry was used to investigate pDMAEMA's capacity to be internalized by bacteria and to determine effects on bacterial cell cycling. pDMAEMA was bacteriostatic against Gram-negative bacteria with MIC values between 0.1-1 mg/mL. MIC values against Gram-positive bacteria were variable. pDMAEMA was active against Gram-positive bacteria around its pK(a) and at lower pH values, while it was active against Gram-negative bacteria around its pK(a) and at higher pH values. pDMAEMA inhibited bacterial growth by binding to the outside of the bacteria, permeabilizing the outer membrane and disrupting the cytoplasmic membrane. By incorporating pDMAEMA with erythromycin, it was found that the efficacy of the latter was increased against Gram-negative bacteria. Together, the results illustrate that pDMAEMA acts in a similar fashion to other cationic biocides.
Collapse
|
13
|
Keely S, Glover LE, Weissmueller T, MacManus CF, Fillon S, Fennimore B, Colgan SP. Hypoxia-inducible factor-dependent regulation of platelet-activating factor receptor as a route for gram-positive bacterial translocation across epithelia. Mol Biol Cell 2009; 21:538-46. [PMID: 20032301 PMCID: PMC2820419 DOI: 10.1091/mbc.e09-07-0573] [Citation(s) in RCA: 40] [Impact Index Per Article: 2.7] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022] Open
Abstract
Results from these studies reveal that some strains of Gram-positive bacteria exploit hypoxia-inducible factor-regulated platelet-activating factor receptor as a means for translocation through intestinal epithelial cells. Mucosal surfaces, such as the lung and intestine, are lined by a monolayer of epithelia that provides tissue barrier and transport function. It is recently appreciated that a common feature of inflammatory processes within the mucosa is hypoxia (so-called inflammatory hypoxia). Given the strong association between bacterial translocation and mucosal inflammatory disease, we hypothesized that intestinal epithelial hypoxia influences bacterial translocation. Initial studies revealed that exposure of cultured intestinal epithelia to hypoxia (pO2, 20 torr; 24–48 h) resulted in a increase of up to 40-fold in the translocation of some strains of Gram-positive bacteria, independently of epithelial barrier function. A screen of relevant pathway inhibitors identified a prominent role for the platelet-activating factor receptor (PAFr) in hypoxia-associated bacterial translocation, wherein pharmacologic antagonists of PAFr blocked bacterial translocation by as much as 80 ± 6%. Extensions of these studies revealed that hypoxia prominently induces PAFr through a hypoxia-inducible factor (HIF)-dependent mechanism. Indeed, HIF and PAFr loss of function studies (short hairpin RNA) revealed that apically expressed PAFr is central to the induction of translocation for the Gram-positive bacteria Enterococcus faecalis. Together, these findings reveal that some strains of Gram-positive bacteria exploit HIF-regulated PAFr as a means for translocation through intestinal epithelial cells.
Collapse
Affiliation(s)
- Simon Keely
- Mucosal Inflammation Program, Department of Medicine, University of Colorado Denver, Aurora, CO 80045, USA.
| | | | | | | | | | | | | |
Collapse
|
14
|
Keely S, Ryan SM, Haddleton DM, Limer A, Mantovani G, Murphy EP, Colgan SP, Brayden DJ. Dexamethasone-pDMAEMA polymeric conjugates reduce inflammatory biomarkers in human intestinal epithelial monolayers. J Control Release 2008; 135:35-43. [PMID: 19110018 DOI: 10.1016/j.jconrel.2008.12.001] [Citation(s) in RCA: 37] [Impact Index Per Article: 2.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/15/2008] [Revised: 11/26/2008] [Accepted: 12/01/2008] [Indexed: 01/10/2023]
Abstract
The mucoadhesive polymer, poly(dimethylamino)ethyl methacrylate, (pDMAEMA), was synthesised by living radical polymerisation and subsequently conjugated by quaternisation reaction to a functionalised anti-inflammatory corticosteroid dexamethasone, to separately yield two conjugates with either 9:1 or 18:1 molar ratios of dexamethasone:polymer respectively. The hypothesis was to test whether the active agent maintained in vitro bioactivity when exposed to the apical side of human intestinal epithelial monolayers, Caco-2 and mucus-covered HT29-MTX-E12 (E12). HPLC analysis indicated high conjugate purity. Similar to pDMAEMA, fluorescently-labelled dexamethasone-pDMAEMA conjugates were bioadhesive to Caco-2 and mucoadhesive to E12. Apical addition of conjugates suppressed mRNA expression of the inflammatory markers, NURR1 and ICAM-1 in E12 following stimulation by PGE(2) and TNF-alpha, respectively. Conjugates also suppressed TNF-alpha stimulated cytokine secretion to the basolateral side of Caco-2 monolayers. Measurement of dexamethasone permeability from conjugates across monolayers suggested that conjugation reduced permeability compared to free dexamethasone. LDH assay indicated that conjugates were not cytotoxic to monolayers. Anti-inflammatory agents can therefore be successfully conjugated to polymers and they retain adhesion and bioactivity and have potential to be formulated for topical administration.
Collapse
Affiliation(s)
- Simon Keely
- School of Agriculture, Food Science and Veterinary Medicine, and UCD Conway Institute, University College Dublin, Dublin 4, Ireland
| | | | | | | | | | | | | | | |
Collapse
|